A method and apparatus for directly or indirectly applying a liquid or pasty application medium to one or both sides of a continuous surface.
The present invention relates to a method and apparatus for directly or indirectly applying a liquid or pasty application medium to one or both sides of a continuous surface.
Methods according to the class and apparatus according to the class are usually used as part of paper-making machines or coating plants in order to provide a continuous surface, for instance a material web composed e.g. of paper, cardboard or a textile material, with one or more layers of application medium, e.g. dye, starch, impregnating fluid or the like, on one or both sides. So-called direct application involves the application of liquid or pasty application medium from an applicator directly onto the surface of the continuous material web which during application is supported on a revolving support surface, e.g. a continuous belt or a counter-roll. Indirect application of the medium, on the other hand, first involves the application of liquid or pasty application medium onto an opposite surface which acts as a carrier face, e.g. the surface of a counter-roll designed as an application roll from where it is transferred in a roll gap, through which the material web passes, from the application roll onto the material web.
To perform the direct or indirect application techniques described above, use is normally made of application devices which either have an application chamber or are fitted with a single nozzle or free-jet nozzle extending in the form of a narrow, long gap across substantially the entire web width. A method and an apparatus used to apply a single trace--which is as far as possible narrow--of liquid or pasty medium, preferably glue, onto a continuous material web are known from DE 195 04 652 A1. For this purpose, the apparatus has a nozzle head with a single nozzle from which the medium is sprayed directly and without contact onto a narrow partial region of the material web.
A method, comparable with the technical solution according to DE 195 04 652 A1, and its associated apparatus are also known from DE 295 06 334 U1. The method according to DE 295 06 334 U1 also involves the application of just one strip-like trace of application medium.